The Official Publication of the Bucks-Mont Astronomical Association, Inc________________________________________________________________________________________________________________________________________

The next BMAA General Meeting is scheduled for Wednesday, April 5 at 8:00p
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Stressful situations will sometimes cement friendships, but attaining good telescope optical alignment will more likely destroy a friendship. It is frustratingly difficult for the observer at the focuser to get the guy tweaking the nuts at the other end to do the right thing at the right time. Use of a video camera, coupled with a light emitting diode (LED) to replace the center dot makes the job faster (even with set-up time of the camera), much less frustrating and often improves results. Moreover, the technique allows one person to do the job - particularly if you have lost all your friends to attaining optical alignment in the past!

The technique requires a video camera at the sight tube or Cheshire eyepiece and perhaps a monitor at the mirror cell. If alignment is done by watching the screen, there is immediate feedback to the turning of the adjustment nuts. This allows for natural hand-eye coordination so necessary to the task of alignment. Also, consider removing the center dot painted on the center of the mirror and carefully scratch away the mirror coating exactly in the center. A 1/8in or smaller area is enough. Now place the LED (I use the same battery-operated light used to illuminate setting circles) behind the mirror. The bright light makes a great target when collimating the scope, with or without the video camera.

In addition to allowing for good hand-eye coordination, the video camera allows for increased scale during the adjustment. The center dot is now plenty big, and so motion is that much easier to judge. Also, the variable light level of the LED permits good collimation in a variety of lighting conditions.

How well does it work? Most of the time I find that when I drop an autocollimator eyepiece in place to complete the job I find it to be close enough that the play in the position of the eyepiece will indicate good alignment without further adjustment. Autocollimation can be achieved by watching the multiple images of the LED and adjusting until they meet in the center! If this is done, a check with the autocollimator in the usual fashion (with a penlight held inside the open end of the tube) reveals proper alignment.

The technique is accurate, fast and much less frustrating. It may even save friendships!

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- BMAA member John Deitz submitted this 'Tips' article. [ -ed]

Img 1: Viewed with the video camera at the eyepiece. Img 2: Keep in mind that any track established by turning an adjustment nut will be 120deg to any other